The primary function of the skin and cornea is to serve as a protective barrier against the environment. Loss of the integrity of portions of the skin or cornea as a result of injury or illness may lead to major disability or even death. Every year in the United States more than 1.25 million people have burns and 6.5 million have chronic skin ulcers caused by pressure, venous stasis, and diabetes mellitus. Many corneal problems are also caused by a loss of corneal epithelial integrity as observed in various diseases such as corneal ulcer, corneal erosion, keratitis and dry eye. Topical administration of drugs and surgery situations can also lead to delay of epithelial wound healing.
Wound healing is a dynamic, interactive process involving soluble mediators, blood cells, extracellular matrix, and parenchymal cells. Wound healing has 3 phases that overlap in time: vascular phase and inflammation, new tissue formation including reepithelialization, and tissue remodelling. Wounds are currently treated by applying an emergency treatment to a wounded site and waiting for the wounds to spontaneously heal via the biological recovering power of their own. However a chronic incomplete reepithelialisation may be observed and may lead to opportunistic infection, irreversible scarring and eventually cornea or skin impairment. Accordingly, the existent agents for wound healing do not have sufficient actions for stimulating reepithelialization so they are problematic in that they cannot completely heal wounds in a short period of time